Queen Elizabeth II, in carriage, travels along Parliament Street to Buckingham Palace with Camilla, the Duchess of Cornwall and Prince Charles, after having lunch in Westminster Hall, London, Tuesday, June 5.

London — Across Britain, neighbors are meeting to share a meal during the four days of Queen Elizabeth’s Diamond Jubilee.

Known as the Big Lunch, the idea is to foster community with some cucumber sandwiches, curry, and conversation. Local volunteers organize the block parties across Britain, with last year’s effort turning out nearly 2 million people.

“I haven’t met people from Turkey before, but … I met some at this party and they are nice,” says Clarissa Ihenacho, a Nigerian resident of south London attending a neighborhood Big Lunch today.

By incorporating the annual Big Lunch into the jubilee, the palace joins successive British governments and parts of civil society who have tried to improve social cohesion in the country. However, what’s driving people apart and how to bring them together again remain heavily disputed in Britain, undercutting many but the most uncontroversial efforts like the Lunch.

“We’re a society of ever decreasing circles. Most of us just meet and hang out with people like ourselves, and we don’t cross many class barriers or indeed racial or religious barriers,” says Phillip Blond, one of the intellectual architects for Prime Minister David Cameron’s social cohesion program called the Big Society.

The reason communities are fragmenting, argues Mr. Blond, is that people reach out and rely on the family and neighbors around them less as the state and the private sector have grown larger and more centralized.

“The state has destroyed the indigenous horizontal relationships of those at the bottom and replaced them with dependency, vertical-type relationships,” says Blond. “Markets have [also] served to concentrate power.”

Is Big Society to blame?

While conservatives traditionally champion privatizing state services, Big Society initiatives try to tap local charities, community co-ops, and volunteer groups to take over some state services. The stated goal: empowering locals.

Some of the initiatives include giving residents in state-subsidized housing and doctors within the national health system more control over how state funds are spent. It also opens up programs like prisoner rehabilitation to charity and church groups.

The program has coincided with deep cuts in government spending in response to the global recession. Labour leader Ed Miliband has criticized the Big Society, saying the government is “cynically attempting to dignify its cuts agenda by dressing up the withdrawal of support with the language of reinvigorating civic society.”

Some on Britain’s left agree that divisions are worsening in Britain, but pin the blame on weakened trade unions, worsening income inequality, and government cuts that take away possibilities for social mobility.

Recent public spending cuts have also decimated the very volunteer groups that the government hoped would step in to take over public services.

A study last month by the think tank Civil Exchange found that the voluntary sector is facing $5 billion of cuts in public funding up to 2016. The study also found that small community organizations were struggling to win government contracts, which tended to go to larger organizations, mainly in the private sector.

“A lot of those groups who were told to participate in the Big Society were having their funding and financial support suddenly cut. I think they were suddenly facing a contradiction,” says Matthew Goodwin, a lecturer at the University of Nottingham.

Similar doubts about the wider Big Society agenda were expressed at a Big Lunch party in Clapham Junction in south London today.

A local mother, Sandra Munoz, has gone to several Big Lunches in the area, including one last year where she met people with whom she later went Christmas caroling.

“In the big city it’s so easy to be very lonely, but things like this make a difference,” says Ms. Munoz, who is wearing a Union Jack bow in her hair. “The more people link together, the more they can do. They can use people’s talents.”

At Big Lunches she tries to introduce people to a local parents volunteer group, which she says volunteered to keep a local library open when the government cut half its staff.

She calls the Big Society a partial success. While she likes the idea of boosting community engagement, she worries it’s enabling cuts.

“If it’s replacing paid staff with volunteers, that’s not great: People need to have jobs,” she says. “But if people didn’t volunteer, things like the library would close down.”

Britain grapples with diversity, integration

Another source of community tension in Britain has been the influx of immigrants. Net immigration has gone from 48,000 in 1997 to a quarter million in 2010. Polls have found that the majority of Britons are uneasy with the pace of immigration. The London Tube attacks in 2005 prompted concerns about how successfully the children of Muslim immigrants were developing British identities.

“If [immigration] happens too quickly, it’s much more difficult for people to integrate. It’s much more difficult to teach English to [a class of] 60 percent non-English kids,” says Alp Mehmet with MigrationWatch UK, a group that advocates dialing back net immigration to 40,000 a year.

At least the spread at the Clapham Junction lunch suggested local comfort with London’s ethnic diversity. Quiches and salads sat on the table beside samosas and pakoras; a Tongan turned a pig on a spit roast while an English native cooked bangers and mash on nearby charcoal.

A local member of parliament rode up on a red bicycle, while the new mayor came by in a black limo. They gave some quick speeches before everyone piled the food – some brought by the residents, others donated from local businesses – onto Union Jack paper plates. Kids ran around the park together, while the adults mingled fitfully for a few hours.

While Munoz has kept in touch with people she met at other Big Lunches and Ihenacho has taken down phone numbers of people she's met today, experts wonder if these lunches are long enough interactions to break down barriers.

“One of the problems with cohesion initiatives is they are often kept very snapshot, very quick, and they tend to build only superficial links between people,” says Mr. Goodwin. “It takes a lot of time and effort.”